The present invention refers to a protection device for a speed sensor.
In general, in order to measure the angular speed of rolling contact bearings, it is well known to use speed sensors which face an encoder which is integral with a rotating race of a rolling contact bearing, and provided with a reading surface which is arranged at a determined distance from the encoder, and it is also well known to protect these speed sensors, and above all their reading surfaces, by means of protection devices, which are installed on the rolling contact bearing and which comprise a housing for the sensor and, according to the case in point, either a bellows made of rubber material which is arranged in such a way as to close the housing, or, in the simplest form of manufacture, a wall which is made of rubber material and which is arranged at the bottom of the housing between the encoder and the reading surface in order to adhere to the reading surface itself and insulate it completely from the outside.
In both the cases which have just been described, the protection device, while having been shown to be sufficiently reliable in terms of providing protection against the majority of external polluting agents, presents some disadvantages when, subsequent to some particular uses of the rolling contact bearing, some particles of mud are present, which, as they can stick to the encoder, can also impact on the reading surface in such a way as to cause progressive wear and therefore reduce the quality of the signal.